* {
  margin: 0;
  padding: 0;
}

html,body,#app {
  width: 100%;
  height: 100%;
  overflow: hidden;

}

#app {
  display: flex;
  flex-direction: column;
  header, footer {
    background: skyblue;
    height: 36px;
    display: flex;
    justify-content: space-around;
    align-items: center;
    color: #fff;
    b {
      &.active {
        color: red;
      }
    }
  }

  main {
    flex: 1;
    overflow-y: scroll;
    overflow-x: hidden;
    height: 100%;
  }
}